Progesterone and estrogen - during the luteal phase, corpus luteum is the main source.

What is luteolysis?

The regression of the corpus luteum if fertilization does not occur.

What is the corpus albicans?

The remnant of the corpus luteum, which is fibrous scar tissue.

Name the three stages of the menstrual cycle.

Follicular, Ovulatory, Luteal.

What marks the beginning of the early follicular phase?

Onset of menses.

What hormone is increased during menses, the beginning of the follicular phase?

FSH increases, which increases estradiol production.

What effect do estradiol and inhibin have on the developing follicle?

They increase the frequency of LH pulses, also begins to suppress FSH by negative feedback.

What are dominant follicles known for doing in the pre-ovulation stage?

Releasing a lot of estradiol and increasing aromatase activity (which favors exponential growth of the follicle and nourishment of the oocyte).

What initiates the LH surge during ovulation?

Sustained exposure to high levels of estradiol, which synthesizes by positive feedback mechanisms.

How does the effect of estradiol change when secreted in a sustained fashion?

Negative feedback of FSH/LH becomes positive feedback.

What happens to levels of estradiol and progesterone in the early luteal phase?

Estradiol declines and progesterone rises (low estrogen:progesterone ratio) due to LH which drives the corpus luteum.

What role does the corpus luteum play in the luteal phase?

Raises progesterone and estradiol to peak levels.

What effect do high levels of progesterone and estradiol have on the follicle during the late luteal phase?

They suppress FSH and LH, keeping them at their lowest levels, which will prevent menses.

When does luteolysis occur?

During the late luteal phase as progesterone and estrogen levels drop off.

What happens to progesterone and estradiol levels at the end of the luteal phase?

They drop drastically to base levels.

What happens to plasma FSH levels during the menses phase?

Begin a very slow rise now that there is no negative feedback from progesterone and estradiol.

What effect does a high level of estradiol have on the responsiveness of the anterior pituitary to GnRH?

Estradiol makes pituitary more sensitive to GnRH and thus more LH is secreted when bound. Constant exposure to estradiol is shown to change negative feedback of LH to pituitary to positive feedback, thus the LH surge.

What receptors develop on theca cells in the secondary follicle?

LH receptors.

What receptors develop on granulosa cells in the secondary follicle?

FSH receptors.

What new feature is given to the follicle in its secondary phase?

Secretes steroid hormones, like estradiol.

In the secondary follicle, what structure develops in response to FSH and estradiol?

Antrum.

In the Graafian follicle, what three hormones are required for max progesterone production?

FSH, LH, and estradiol.

What cells contain FSH receptors?

Granulosa cells.

What cells contain LH receptors?

Granulosa and theca cells.

What steroids (hormones) are produced by granulosa cells during the Graafian follicle phase?

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